Hi 'Nando,
In studying your images of 'my' long-time breech chamber I cannot but repeat putting the stress on how unbelievably early this tiny piece is: its slender High-Gothic general shape, reflecting the even earlier Romanic style still rounded throughout, are clear indices of a date of origin of ca. 1440!
They should in no way be confounded with the much shorter, stouter but also round Early-Renaissance objects of ca. 1540, like the ones salvaged from the Mary Rose, or the 'Portuguese' sample in Marcus' collection.
http://www.vikingsword.com/vb/showthread.php?t=17547
Best,
Michl